1. Field of the Invention
This invention relates to an image forming apparatus using the electrophotographic process, and a process cartridge detachably mountable to the main body of the image forming apparatus or a developing device made into a cartridge, and particularly to an image forming system comprised of storing means carried on the process cartridge or the developing device, and indicating means for detecting the remaining amount of developer by the use of developer amount detecting means disposed in the process cartridge or the developing device, and indicating the result thereof.
The term xe2x80x9celectrophotographic image forming apparatusxe2x80x9d covers, for example, an electrophotographic copier, an electrophotographic printer (such as an LED printer or a laser beam printer), an electrophotographic facsimile apparatus, etc.
Also, the cartridge detachably mountable to the main body of the electrophotographic image forming apparatus refers to at least one of an electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, developing means for supplying a developer to the electrophotographic photosensitive member, and cleaning means for cleaning the electrophotographic photosensitive member constructed detachably mountably to the main body of the electrophotographic image forming apparatus. Particularly, the process cartridge refers to at least one of the charging means, the developing means and the cleaning means and the electrophotographic photosensitive member constructed integrally with each other, and made detachably mountable to the main body of the electrophotographic image forming apparatus.
2. Related Background Art
An image forming apparatus of the electrophotographic type such as a copier or a laser beam printer applies light modulated in accordance with image information to a photosensitive member to thereby form a latent image thereon, supplies a developer (toner) which is a developing material to the latent image by developing means to thereby visualize the latent image, and further transfers the image from the photosensitive member to a recording medium to thereby form an image on the recording medium. A developer container containing the developer therein is connected to the developing means, and the developer is consumed by images being formed.
In such an image forming apparatus, there is a process cartridge system in which with a view to achieve the simplicity of the interchange and maintenance of expendibles such as the electrophotographic photosensitive member and the developer, the electrophotographic photosensitive member, and developing means, charging means and cleaning means as process means for acting on the electrophotographic photosensitive member, and further a developer container, a developer reservoir or the like are made integral with one another as a process cartridge which is detachably mountable to the main body of the image forming apparatus. According to the process cartridge system, the maintenance of the apparatus can be done by the user himself without resorting to a serviceman and therefore, the operability of the apparatus can be markedly improved. So, the process cartridge system is widely used in electrophotographic image forming apparatus.
Also, for example, among color image forming apparatuses having developing means of a plurality of colors, there is one in which when the degrees of consumption of the respective developing means differ from one another, a developing cartridge of each color into which the developing means of each color and a developer container are made is made detachably mountable to the image forming apparatus so as to be individually interchangeable.
In the image forming apparatus of such a cartridge type, the user can interchange the cartridge, for example, at a point of time whereat the developer has become exhausted, to thereby form an image again. Therefore, such an image forming apparatus is sometimes provided with means for detecting that the developer has been consumed, and informing the user of it, i.e., a developer amount detecting device.
The developer amount detecting device is provided with developer amount detecting means capable of detecting the developer-remaining-amount level in the cartridge or the main body of the image forming apparatus in order to enable how much developer usable for image formation remains in the cartridge to be known at any time.
Particularly, there are image forming apparatuses in which not only the user is informed that the developer has become exhausted, but also the amount of the developer is sequentially detected and the user is informed of it, whereby the convenience to the user is further improved. Among such image forming apparatuses, there is one in which how many percent of the amount when unused the developer remains is calculated and sequentially reported to the user or the xe2x80x9cno developerxe2x80x9d indication showing that the developer has been decreased to such a degree that image formation of a predetermined quality cannot be effected is done to thereby warn the user that the remaining amount of the developer has become small before a bad image occurs.
As a system of the developer amount detecting means, there is a flat antenna system. A flat antenna is a pattern provided with a pair of electrically conducting portions formed in parallel to each other at a predetermined interval, and disposed at a position on the side of a developer container which is in contact with the developer, and utilizes the fact that the capacitance is changed by the presence or absence of the developer on the surface of the pattern.
The flat antenna is disposed so that as the developer in the developer container is decreased, the area of contact between the developer and the flat antenna may decrease, whereby it becomes possible to make the remaining amount of the developer and the capacitance of the flat antenna correspond to each other, and by measuring the capacitance of the flat antenna, it is possible to know the remaining amount of the developer in the developer container at any time. The capacitance of the flat antenna can be known by a constant AC bias being applied to one of the pair of electrically conducting portions, and from an electric current flowing through the other electrically conducting portion at that time.
Actually, even if the developer in the developer container is gradually decreased, a slight amount of developer adheres to and remains on the flat antenna and in order to remove it, an antenna cleaning member is provided and the surface of the flat antenna is cleaned with the rotation of agitating means.
However, by the cleaning of the surface of the antenna, the output of the flat antenna is fluctuated at a surface cleaning cycle period. So, such statistical processing as taking the mean value in conformity with the cycle period or selecting a minimum value is carried out to thereby decide upon the developer-remaining-amount level.
Also, as another system of the developer amount detecting means, there is developer amount detecting means of the plate antenna type in a developing system wherein an AC bias is applied to a developer bearing member disposed in opposed relationship with a photosensitive member to thereby develop a latent image on the photosensitive member.
The plate antenna is constituted by a metal plate provided in parallel to the developer carrying member, and utilizes the fact that the capacitance between the plate antenna and the developer bearing member changes in conformity with the amount of non-conductive developer present between the two.
If the space between the plate antenna and the developer bearing member is filled up with the developer, the capacitance becomes greater, and as the developer is decreased, the air increases between the two and the capacitance becomes smaller. Accordingly, by predetermining the relation between the capacitance between the plate antenna and the developer bearing member and the amount of developer, to thereby measure the capacitance, the developer amount level can be detected.
The capacitance can be found by measuring an electric current flowing through the plate antenna when the AC bias is applied to the developer bearing member. That is, the developer amount detecting system detects the developer-remaining-amount level during image formation when the developer bias is applied to the developer bearing member.
The amount of developer detected by such developer amount detecting means is indicated in indicating means to inform the user of it. The user can judge by looking at the indication that the developer will soon become exhausted, so it would be better to prepare the next cartridge, or that the developer is present sufficiently for a great deal of print to be effected, and can carry out the printing work efficiently and can use the cartridge effectively.
However, even if provision is made of the developer amount detecting means capable of detecting the developer-remaining-amount level as described above, there may occur an error between the amount of developer remaining in the developer container and the detected value by the developer amount detecting means.
For example, the absolute value of the capacitance between the developer bearing member and the plate antenna is affected by the positional relation between the two in such a manner that even when the developer is absent, the aforementioned absolute value becomes greater if the distance between the two is short, and becomes smaller if the distance between the two is long. That is, when the detection of the developer-remaining-amount level is effected by a present capacitance value alone, there is the possibility of outputting a detected value widely different from the actual developer remaining amount.
Accordingly, when the detected value at the full of the developer is greater in capacitance than the initially set (supposed) value, an amount greater than the actual developer-remaining-amount is estimated and the developer may become exhausted before warning and an image having a blank area may occur. Conversely, when the detected value at the full of the developer is smaller in capacitance than the initially set (supposed) value, an amount smaller than the actual developer-remaining-amount is estimated, and in spite of a great deal of developer remaining in the developer container, the no-developer warning may be given, and if the process cartridge is interchanged in accordance with the warning, a great deal of developer will be wasted and this will be the waste of resources.
Also, when a great amount of developer fills the developer container, it will become difficult to generally effect accurate detection of the amount of developer by only one developer detecting means.
The present invention has as its object to provide an image forming apparatus in which the amount of developer can generally be successively and accurately detected and an appropriate cartridge interchange time is shown and the occurrence of bad images can be prevented and the waste of a developer and recording media can be eliminated, a cartridge detachably mountable to the image forming apparatus, and a method of controlling the image forming apparatus.
The cartridge detachably mountable to the main body of the image forming apparatus according to the present invention comprises a developer container, first developer detecting means for outputting the detection value of the developer-remaining-amount in the developer container, second developer detecting means for outputting the detection value of the developer-remaining-amount in the developer container, and storing means for storing therein information regarding the developer-remaining-amount, the storing means having an area for storing therein data regarding the developer-remaining-amount from the second developer detecting means in conformity with the result of the comparison between the detection value of the developer amount from the first developer detecting means and a predetermined value.
In a cartridge detachably mountable to the main body of another image forming apparatus according to the present invention, the storing means has an area for storing therein the detection value of the developer-remaining-amount from the second developer detecting means when the detection value of the developer-remaining-amount has become a value within a predetermined range as the result of the comparison between the detected value of the developer-remaining-amount from the first developer detecting means and a predetermined value.
In a cartridge detachably mountable to the main body of another image forming apparatus according to the present invention, the storing means has an area for storing therein a value obtained by calculation-processing a plurality of detection values of the developer-remaining-amount from the second developer detecting means when the detected value of the developer-remaining-amount has become a value within a predetermined range as the result of the comparison between the detection value of the developer-remaining-amount from the first developer detecting means and a predetermined value.
In a cartridge detachably mountable to the main body of another image forming apparatus according to the present invention, the storing means has an area for storing therein the developer-remaining-amount obtained by calculation-processing the detection value of the developer-remaining-amount from the second developer detecting means by a signal processing device in the main body of the image forming apparatus when the detection value of the developer-remaining-amount has become a value within a predetermined range as the result of the comparison between the detected value of the developer-remaining-amount from the first developer detecting means and a predetermined value.
In a cartridge detachably mountable to the main body of another image forming apparatus according to the present invention, the storing means has an area for storing therein calculation formula information obtained by calculation-processing by the use of the detection value of the developer amount from the first developer detecting means and the detection value of the developer amount from the second developer detecting means by a signal processing device in the main body of the image forming apparatus when as the result of the comparison between the detected value of the developer-remaining-amount from the first developer detecting means and a predetermined value, the detection value of the developer-remaining-amount has become equal to the predetermined value.
In a cartridge detachably mountable to the main body of another image forming apparatus according to the present invention, the storing means has an area for comparing the detection value of the developer-remaining-amount from the first developer detecting means and a predetermined value with each other, repetitively detecting the detection value of the developer-remaining-amount from the second developer detecting means until the detection value of the developer-remaining-amount becomes greater than the predetermined value, and storing therein the minimum value of the detected detection values of the developer-remaining-amount.
In an image forming apparatus according to the present invention comprising a cartridge comprising a developer container, first and second developer detecting means for outputting the detection values of the developer-remaining-amount in the developer container, and storing means for storing therein information regarding the developer-remaining-amount, and signal processing means for calculation-processing the detection value of the developer-remaining-amount, the signal processing means causes data regarding the developer-remaining-amount from the second developer detecting means to be stored in the storing means in conformity with the result of the comparison between the detection value of the developer amount from the first developer detecting means and a predetermined value, and calculates the developer-remaining-amount by the use of the stored data.
In another image forming apparatus according to the present invention, the detection value of the developer-remaining-amount from the second developer detecting means is stored in the storing means when the detection value of the developer-remaining-amount has become a value within a predetermined range as the result of the comparison between the detection value of the developer-remaining-amount from the first developer detecting means and a predetermined value, and the developer-remaining-amount is calculated by the use of the stored detection value of the developer-remaining-amount.
In another image forming apparatus according to the present invention, a plurality of detection values of the developer-remaining-amount from the second developer detecting means are calculated when the detection value of the developer-remaining-amount has become a value within a predetermined range as the result of the comparison between the detection value of the developer-remaining-amount from the first developer detecting means and a predetermined value, and the result is stored in the storing means, and the developer-remaining-amount is calculated by the use of the stored detection value of the developer-remaining-amount.
In another image forming apparatus according to the present invention, calculation formula information calculated from the developer-remaining-amount calculated from the detection value of the developer-remaining-amount from the first developer detecting means and the detection value of the developer-remaining-amount from the second developer detecting means is stored in the storing means when as the result of the comparison between the detection value of the developer-remaining-amount from the first developer detecting means and a predetermined value, the detection value of the developer-remaining-amount has become equal to the predetermined value, and the developer-remaining-amount is calculated from the detection value of the developer-remaining-amount from the second developer detecting means and the calculation formula information.
In another image forming apparatus according to the present invention, the signal processing means compares the detection value of the developer-remaining-amount from the first developer detecting means and a predetermined value, and repetitively detects the detection value of the developer-remaining-amount from the second developer detecting means until the detection value of the developer-remaining-amount becomes greater than the predetermined value, and causes the minimum value of the detected detection values of the developer-remaining-amount to be stored in the storing means, and calculates the developer-remaining-amount by the use of the minimum value of the detection values of the developer-remaining-amount stored in the storing means when the detection value of the developer-remaining-amount from the first developer detecting means has become equal to or greater than the predetermined value.
Another image forming apparatus according to the present invention further comprises indicating means, and the signal processing means transmits the calculated developer-remaining-amount to the indicating means or an external indicating instrument.
A method of controlling an image forming apparatus according to the present invention to which is detachably mountable a cartridge comprising a developer container, first and second developer detecting means for outputting the detection values of the developer-remaining-amount in the developer container, and storing means for storing therein information regarding the developer-remaining-amount, and which has signal processing means for calculation-processing the detection value of the developer-remaining-amount, comprises the step of outputting the detection value of the developer-remaining-amount by the first developer detecting means with the power source of the main body of the image forming apparatus switched on, the step of comparing the detection value of the developer-remaining-amount outputted by the first developer detecting means and a predetermined value with each other, and the step of storing in storing means data regarding the developer-remaining-amount outputted by the second developer detecting means, in conformity with the result of the comparison at the comparing step.
Another method of controlling an image forming apparatus according to the present invention comprises the step of storing in the storing means the detection value of the developer-remaining-amount outputted by the second developer detecting means when at the comparing step, the detection value of the developer-remaining-amount is a value within a predetermined range.
Another method of controlling an image forming apparatus according to the present invention comprises the step of calculating a plurality of detection values of the developer-remaining-amount outputted by the second developer detecting means by the signal processing means, and thereafter storing them in the storing means when at the comparing step, the detection value of the developer-remaining-amount is a value within a predetermined range.
Another method of controlling an image forming apparatus according to the present invention comprises the step of detecting the detection value of the developer-remaining-amount by the second developer detecting means when at the comparing step, the detection value of the developer-remaining-amount is greater than the predetermined value, and the step of calculating the developer-remaining-amount by the use of the detection value of the developer-remaining-amount read from the storing means.
Another method of controlling an image forming apparatus according to the present invention comprises the step of calculating calculation formula information from the detection value of the developer-remaining-amount outputted from the first developer detecting means and the detection value of the developer-remaining-amount outputted from the second developer detecting means when at the comparing step, the detection value of the developer-remaining-amount is the predetermined amount, and the step of calculating the developer-remaining-amount by the use of the calculation formula information.
Another method of controlling an image forming apparatus according to the present invention comprises the step of detecting the detection value of the developer-remaining-amount outputted from the second developer detecting means and storing the detection value in the storing means when at the comparing step, the detection value of the developer-remaining-amount is greater than the predetermined value, and further repetitively detecting the detection value of the developer-remaining-amount outputted from the second developer detecting means until the detection value of the developer-remaining-amount becomes a value greater than the predetermined value, and storing in the storing means the minimum value of the detected detection values of the developer-remaining-amount.
Another method of controlling an image forming apparatus according to the present invention further comprises the step of transmitting the developer-remaining-amount calculated by the use of the detection value of the developer-remaining-amount stored in the storing means to indicating means in the image forming apparatus or an external indicating instrument.
According to the present invention, there is the effect that the developer-remaining-amount can generally be detected successively and accurately, and an appropriate cartridge interchange time can be shown to the user to thereby obviate the occurrence of bad images, and eliminate the waste of the developer and the recording medium.